One method of analyzing a failing semiconductor device, or a Device under Test (DUT) involves the use of Thermal Induced Voltage Alteration tool (TIVA) or Optical Beam Induced Resistance Change (OBIRCH) that make use of a scanning laser source to thermally induce voltage or current changes in the DUT. The TIVA uses a laser (Infra Red spectrum) to scan and thermally induce resistances changes and then monitor a voltage changes. The OBIRCH works similarly to the TIVA, but uses a laser to thermally activate the fail site and then monitor the current fluctuation. Thus they work on the principle that they sense variations at the power supply to the DUT. In other words they sense leakage currents at a DC level while a laser probe is used to scan across the DUT as illustrated in FIG. 1. By scanning back and forth with the laser over the DUT surface along a path, as indicated by reference numeral 100, the TIVA produces localized heating of the circuitry. This impacts the DC power supply reading as measured by the TIVA, allowing the TIVA to identify failure sites that produce leakage current. Typically the TIVA provides a visual picture of the DUT and identifies, by means of spots on the picture, the leakage current error sites. This is done by monitoring and collecting the x-y coordinate information of the laser probe at the time the DC power supply variation is identified. In addition the TIVA produces a die spot on the stored image of the DUT.
However, the TIVA is not capable of identifying and mapping failure sites that have a small AC signal fluctuation that is superimposed on a large DC level, thus severely limiting the use of the TIVA to the identification small AC signal and mapping of only a limited set of error conditions.
The present invention provides new applications for the TIVA and provides the means of effectively using the TIVA to identify and map other error conditions on a DUT.